1. Field of the Disclosure
The present disclosure relates to an organic light emitting device and an organic light emitting display device using the same.
2. Discussion of the Related Art
Organic light emitting display devices are self-emitting display devices, and have a better viewing angle and contrast ratio than liquid crystal display (LCD) devices. Also, since organic light emitting display devices do not need a separate backlight, it is possible to make thee devices lighter and thinner. Organic light emitting display devices also have excellent power consumption characteristics compared to LCD devices and the other flat panel display devices. Furthermore, the organic light emitting display devices are driven with a low direct current (DC) voltage, have a fast response time, and are low in manufacturing cost.
In organic light emitting display devices, an electron and a hole are respectively injected from a cathode and an anode into an emitting material layer, and, when an exciton in which the injected electron and hole are combined is shifted from an excited state to a base state, light is emitted. In this case, the types of organic light emitting display devices are categorized into a top emission type, a bottom emission type, and a dual emission type according to an emission direction of light, and categorized into a passive matrix type and an active matrix type according to a driving type.
Accordingly, when scan signals, data signals, electricity and the like are supplied to a plurality of sub-pixels disposed in the form of a matrix, organic light emitting devices may display an image by allowing the selected sub-pixels to emit light. In this case, the sub-pixels include an organic light emitting device including a thin film transistor (TFT) including a switching thin film transistor, a driving thin film transistor and a capacitor, a first electrode connected to the driving transistor included in the thin film transistor, an organic layer, and a second electrode.
Herein, the organic layer may include a plurality of layers facilitating the injection and transport of electrons and holes, and an emission layer, and organic light emitting devices having the above structure have problems that the difference in band gap may disturb the charge balance, cause the transporting ability of holes to deteriorate, and cause the service life to be shortened.
Further, devices in the related art are advantageous in terms of light emission characteristics, but have a low glass transition temperature and very poor thermal stability. Thus, when the devices are subjected to high temperature deposition process under vacuum, there are shortcomings such as deterioration of material characteristics and the like. Herein, since the efficiency of consumption power=(π/voltage)×current efficiency, the efficiency of consumption power is inversely proportional to the voltage. That is, if consumption power of an organic light emitting device is to be decreased, the power efficiency needs to be high, but devices in the related art have a high driving voltage and thus are not significantly advantageous in terms of consumption power.
Accordingly, there is a need for developing various devices which may improve the service-life characteristics of the organic light emitting device and may improve consumption power characteristics while the devices may be applied to large areas.